Conforming bone stabilization receiver

ABSTRACT

A receiver for engaging a bone stabilizing element includes a receiver portion connectable to the stabilizing element, and a base portion connectable to a bone of a patient. The base portion may connect to the bone with a bone screw, for example a polyaxial bone screw, and the receiver portion may connect to the stabilizing element, for example a rod, using a set screw. The receiver portion and the base portion are slideably connected to each other, coupled and constrained in relative movement, by overlapping portions. Axial rotation between the receiver portion and the base portion is enabled by changing the relative dimensions of overlapped portions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 16/173,303 filed Oct. 29, 2018 (published as U.S.Pat. Pub. No. 2019/0059952), which is a continuation application of U.S.patent application Ser. No. 15/665,567 filed Aug. 1, 2017 (now issued asU.S. Pat. No. 10,143,496), which is a continuation application of U.S.patent application Ser. No. 14/799,607, filed Jul. 15, 2015 (now issuedas U.S. Pat. No. 9,750,541), which is a continuation of U.S. patentapplication Ser. No. 13/152,850, filed Jun. 3, 2011 (now issued as U.S.Pat. No. 9,113,960), which claims priority to U.S. ProvisionalApplication 61/352,680 (expired), all of which are hereby incorporatedby reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to the stabilization of the spine, andparticularly the stabilization of multiple vertebral levels, preservingnatural motion within therapeutic boundaries.

BACKGROUND OF THE INVENTION

The vertebrate spine is the axis of the skeleton on which a substantialportion of the weight of the body is supported. In humans, the normalspine has seven cervical, twelve thoracic and five lumbar segments. Thelumbar spine sits upon the sacrum, which then attaches to the pelvis,and in turn is supported by the hip and leg bones. The bony vertebralbodies of the spine are separated by intervertebral discs, which act asjoints and allow known degrees of flexion, extension, lateral bending,and axial rotation.

The typical vertebra has a thick anterior bone mass called the vertebralbody, with a neural (vertebral) arch that arises from the posteriorsurface of the vertebral body. The centra of adjacent vertebrae aresupported by intervertebral discs. Each neural arch combines with theposterior surface of the vertebral body and encloses a vertebralforamen. The vertebral foramina of adjacent vertebrae are aligned toform a vertebral canal, through which the spinal sac, cord and nerverootlets pass. The portion of the neural arch which extends posteriorlyand acts to protect the spinal cord's posterior side is known as thelamina. Projecting from the posterior region of the neural arch is thespinous process.

The vertebrae also contains four articular processes that extend fromthe posterior region of the vertebra. There are two articular processeson the left side of the vertebra and two articular processes on theright side of the vertebra. Two of the four processes (one on the leftand one on the right) extend upwards from the top of the laminae and arereferred to as the superior articular processes. The other two processes(again one on the left and one on the right) extend downwards from thebottom of the laminae and are referred as the inferior articularprocesses. In a healthy spine the left and right superior articularprocesses of a vertebra form synovial joints with the left and rightinferior articular processes of the superior adjacent vertebra. Thesejoints are also referred to as facet joints. The facet joints aresynovial joints as the joints are encapsulated with connective tissueand lubricated by synovial fluid. The joint faces are also covered withsmooth cartilage, which acts to reduce friction and absorb shock.

The intervertebral disc primarily serves as a mechanical cushionpermitting controlled motion between vertebral segments of the axialskeleton. The normal disc is a unique, mixed structure, comprised ofthree component tissues: the nucleus pulpous (nucleus), the annulusfibrosus (annulus) and two vertebral end plates. The two vertebral endplates are composed of thin cartilage overlying a thin layer of hard,cortical bone which attaches to the spongy, richly vascular, cancellousbone of the vertebral body. The end plates thus act to attach adjacentvertebrae to the disc. In other words, a transitional zone is created bythe end plates between the malleable disc and the bony vertebrae.

The annulus of the disc is a tough, outer fibrous ring which bindstogether adjacent vertebrae. The fibrous portion, which is much like alaminated automobile tire, measures about 10 to 15 millimeters in heightand about 15 to 20 millimeters in thickness. The fibers of the annulusconsist of fifteen to twenty overlapping multiple plies, and areinserted into the superior and inferior vertebral bodies at roughly a 40degree angle in both directions. This configuration particularly resiststorsion, as about half of the angulated fibers will tighten when thevertebrae rotates in either direction, relative to each other. Thelaminated plies are less firmly attached to each other.

Immersed within the annulus is the nucleus. The healthy nucleus islargely a gel-like substance having high water content, and like air ina tire, serves to keep the annulus tight yet flexible. The nucleus-gelmoves slightly within the annulus when force is exerted on the adjacentvertebrae while bending, lifting, and other motions.

The spinal disc may be displaced or damaged due to trauma, disease,degenerative defects, or wear over an extended period. A disc herniationoccurs when the annulus fibers are weakened or torn and the inner tissueof the nucleus becomes permanently bulged, distended, or extruded out ofits normal, internal annulus confines. The mass of a herniated orslipped nucleus tissue can compress a spinal nerve, resulting in legpain, loss of muscle control, or even paralysis. Alternatively, withdiscal degeneration, the nucleus loses its water binding ability anddeflates, as though the air had been let out of a tire. Subsequently,the height of the nucleus decreases causing the annulus to buckle inareas where the laminated plies are loosely bonded. As these overlappinglaminated plies of the annulus begin to buckle and separate, eithercircumferential or radial annular tears may occur, which may contributeto persistent or disabling back pain. Adjacent, ancillary spinal facetjoints will also be forced into an overriding position, which may createadditional back pain.

Whenever the nucleus tissue is herniated or removed by surgery, the discspace will narrow and may lose much of its normal stability. In manycases, to alleviate back pain from degenerated or herniated discs, thenucleus is removed and the two adjacent vertebrae are surgically fusedtogether. While this treatment alleviates the pain, all discal motion islost in the fused segment. Ultimately, this procedure places a greaterstress on the discs adjacent to the fused segment as they compensate forlack of motion, perhaps leading to premature degeneration of thoseadjacent discs.

As an alternative to vertebral fusion, various prosthetic discs havebeen developed. The first prosthetics embodied a wide variety of ideas,such as ball bearings, springs, metal spikes and other perceived aids.These prosthetics are all made to replace the entire intervertebral discspace and are large and rigid. Many of the current designs forprosthetic discs are large and inflexible. In addition, prosthetic discsizes and other parameters limit the approach a surgeon may take toimplant the devices.

For example, many of these devices require an anterior implantationapproach as the barriers presented by the lamina and, more importantly,the spinal cord and nerve rootlets during posterior or posterior lateralimplantation is difficult to avoid. Anterior implantation involvesnumerous risks during surgery. Various organs present physical obstaclesas the surgeon attempts to access the damaged disc area from the frontof the patient. After an incision into the patient's abdomen, thesurgeon must navigate around organs and carefully move them aside inorder to gain access to the spine. Additionally, the greater vessels arepresented during an anterior approach. These greater vessels (the aortaand vena cava) risk exposure and injury during surgery. One risk to thepatient from an anterior approach is that their organs may beinadvertently damaged during the procedure. Another risk to the patientfrom an anterior approach is that their greater vessels may be injuredduring surgery. These constraints and/or considerations have led tonovel prosthetic disc designs as disclosed in co-pending U.S. patentapplication Ser. No. 11/246,149, which is incorporated herein byreference in its entirety.

A posterior approach to intervertebral disc implantation avoids therisks of damaging body organs and vessels. Despite this advantage, aposterior approach raises other difficulties that have discouraged ituse. For instance, a posterior approach can introduce a risk of damagingthe spinal cord. For example, vertebral body geometry allows onlylimited access to the intervertebral discs and a posterior approachusually requires the retraction of the spinal cord to one side, or theother, or both during surgery. Because of the spinal chord's importancein the human body, reducing exposure of the spinal cord to injury duringsurgery is important. Thus, the key to successful posterior or posteriorlateral implantation is avoiding contact with the spinal cord, as wellas being able to place an implant through a limited area due to theshape of the vertebral bones. These constraints and/or considerationshave led to novel prosthetic disc designs as disclosed in co-pendingU.S. patent application Ser. No. 10/909,210, which is incorporatedherein by reference in its entirety.

Another known approach to the intervertebral space is the transforminalapproach. This approach has been used in interbody lumbar fusionsurgeries and involves approaching the intervertebral space through theintervertebral foramina. This approach often requires the removal of onefacet joint on either the left or right side. After removal, the surgeongains access to the intervertebral space through the intervertebralforamina. One drawback to this method is that the removal of a facetjoint may lead to instability of the spine. Despite this drawback, inmany instances the transforminal approach is favored in that there isreduced risk to the organs and greater vessels (as compared to theanterior approach) and reduced risk to the spinal cord (as to theposterior approach). A stabilization structure may be utilized on theposterior region of the spine to reduce the potential instabilitycreated by the facet removal.

SUMMARY OF THE INVENTION

In accordance with the invention, a device is provided for connecting astabilizing member to one or more bones of a patient, comprising a basehaving a first and second axis, the base including means for connectingthe base to the bone; a receiver having a first and second axis, thereceiver positionable upon the base and including means for connectingthe receiver to the stabilizing member; a slide rail associated with oneof the base or the receiver; and a projection connected to the other ofthe base or receiver associated with the slide rail, insertable inapposition to the slide rail, operative when inserted to limitrespective movement of the base and the receiver in a direction alignedwith their respective first axes, and to slideably limit relativemovement of the base and the receiver in a direction aligned with theirrespective second axes.

Various embodiments of the invention further include: a secondprojection connectable to one of the base and the receiver, operable tolimit a lateral movement of the receiver relative to the base; means forconnecting the base to the bone includes a chamber for a bone screw, andmeans for clamping the head of the bone screw within the chamber; meansfor connecting the receiver to the stabilizing member includes a yokeand a set screw; the projection is polymeric; the slide rail is a flangeextending along at least two sides of the base or receiver to which itis associated; the slide rail is a face of a channel formed in the baseor receiver to which it is associated; the projection is a flangeextending along at least two sides of the base or receiver which is notassociated with the slide rail; the projection lies between the sliderail and a portion of the base or receiver which is not associated withthe slide rail; the first axes of the receiver and the base extend in adirection corresponding to a sagittal plane of the body, when the baseis connected to the body, and the receiver is positioned upon the base;the receiver slides upon the base in a direction corresponding to theirmutual second axes; a gap between the inserted projection and the sliderail, enables a therapeutically beneficial amount of relative movementbetween the receiver and the base, in a direction corresponding to thefirst axes; at least two receivers are connected to bones of thepatient, the stabilizing member extending between adjacent receivers; aportion of the stabilizing member is connected to the device, andanother portion of the stabilizing member is connected to the patient byanother means; the one or more bones of a patient are selected from thegroup consisting of: toe, foot, ankle, calf, knee, thigh, hip, spine,shoulder, head, jaw, upper arm, elbow, lower arm, wrist, hand, finger;the stabilizing member is either rigid or flexible.

Alternatively, a device of the invention is provided for connecting astabilizing member to one or more bones of a patient, comprising: a basehaving a first and second axis, the base including a base threadedfastener for connecting the base to the bone; a receiver having a firstand second axis, the receiver slidingly positionable upon the base andincluding a receiver threaded fastener for connecting the receiver tothe stabilizing member; a slide rail associated with one of the base orthe receiver; a projection connected to the other of the base orreceiver to which the slide rail is associated, insertable in appositionto the slide rail, operative when inserted to limit respective movementof the base and the receiver in a direction aligned with theirrespective first axes, and to slideably limit relative movement of thebase and the receiver in a direction aligned with their respectivesecond axes; and an access channel extending in a direction of the firstaxes of each of the base and the receiver, in communication with thebase threaded fastener.

Other embodiments include: the receiver threaded fastener is disposedwithin the channel; and the receiver and base threaded fasteners arepositioned within the access channel when the device is connected to thepatient.

In another alternative, a device of the invention provides forconnecting a stabilizing member to one or more bones of a patient,comprising: a base having a first and second axis, the base including abase threaded fastener for connecting the base to the bone; a receiverhaving a first and second axis, the receiver slidingly positionable uponthe base and including a receiver threaded fastener for connecting thereceiver to the stabilizing member; an elongated aperture connected toone of the base or the receiver; a projection connected to the other ofthe base or receiver to which the elongated aperture is connected, theprojection projecting within the elongated aperture, operative therebyto therapeutically limit respective movement of the base and thereceiver in a direction aligned with their respective first axes, and toslideably and therapeutically limit relative movement of the base andthe receiver in a direction aligned with their respective second axes toa greater extent than the movement aligned with their respective firstaxes; and an access channel extending in a direction of the first axesof each of the base and the receiver, in communication with the basethreaded fastener

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic cross section of a stabilizing receiver inaccordance with the invention;

FIGS. 1A-1C depict alternative engagement embodiments of the receiver ofFIG. 1;

FIG. 2 is a perspective view of a stabilizing receiver in accordancewith the invention, shifted in a first direction;

FIG. 3 illustrates the receiver in accordance with FIG. 2, shifted in asecond direction;

FIG. 4 is a cross sectional illustration of the receiver of FIG. 2,taken along a longitudinal centerline of the receiver;

FIG. 5 is a cross sectional illustration of the receiver of FIG. 2,taken along a longitudinal centerline of the receiver, rotated 90degrees with respect to FIG. 4;

FIG. 6 is an alternative perspective view of the receiver of FIG. 2,together with a bone screw to which it is connected;

FIG. 7 is a schematic cross section of a stabilizing receiver of theinvention, provided with a lateral offset;

FIG. 8 is a perspective view of a stabilizing receiver having a lateraloffset, in accordance with the invention;

FIG. 9 is a schematic view of the receiver of FIG. 8;

FIG. 10 is a cross sectional illustration of the receiver of FIG. 8,taken along a longitudinal centerline of the receiver;

FIG. 11 is a cross sectional illustration of a receiver of the inventionhaving an offset portion, taken along a longitudinal centerline of thereceiver;

FIG. 12 is a schematic cross section of a stabilizing receiver inaccordance with the invention, provided with an receiver assembly offsetin three dimensions;

FIG. 13 is a schematic cross section of a stabilizing receiver inaccordance with the invention, enabling conforming shifting in twodimensions;

FIG. 13A is a schematic cross section of an upper portion of thestabilizing receiver of FIG. 13, rotated 90 degrees with respect to FIG.13;

FIG. 14 is a perspective view of a stabilizing receiver in accordancewith the invention, enabling conforming shifting in two dimensions;

FIG. 15 is a cross sectional illustration of the receiver of FIG. 14,taken along a longitudinal centerline of the receiver;

FIG. 16 is a cross sectional illustration of the receiver of FIG. 14,taken along a longitudinal centerline of the receiver, rotated 90degrees with respect to FIG. 15;

FIG. 17 is a perspective view of two receivers of FIG. 2 connected to astabilizing means;

FIGS. 18A-B are schematic illustrations of three receivers correspondingto the receiver of FIG. 13, stabilizing three bones of a patient andusing a rigid stabilizing means;

FIGS. 19A-B are schematic illustrations of three receivers correspondingto the receiver of FIG. 2, stabilizing three bones of a patient andusing a flexible stabilizing means; and

FIG. 20 is a schematic illustration of receivers in accordance with theinvention stabilizing elongated bones of a patent.

DETAILED DESCRIPTION OF THE INVENTION

During certain surgical procedures on bones, including but not limitedto the spine, it may become necessary to supplement or even entirelyreplace the functionality of one or more joints. Attendant with theseprocedures is a desire to mimic, as best as possible, a natural movementof a healthy joint. Various devices and methods are known for fixingadjacent vertebrae, one to the other, while enabling movement withinconstraints, such as are disclosed in U.S. Patent ApplicationPublication Nos. 2009/0299411 to Laskowitz et al., 2009/0240285 toFriedrich et al., or 2009/0240286 to Friedrich et al., the contents ofeach of which are incorporated by reference herein in their entirety.The present invention provides a device and method which may be usedalone, or in combination with such devices and methods, for providing anadditional or alternative range of motion, within constraints, therebyimproving a therapeutic benefit to the patient, and providing additionaloptions for the medical practitioner.

With reference to FIG. 1, a stabilizing receiver 100 of the invention isformed with an anchor base 110 operative to securely connect receiver100 to an anchor 102. Anchor base may connect to anchor by any knownmeans, including a threadable attachment, set screw, welding, or may beintegrally formed with anchor 200. Anchor 200 includes any means forattaching anchor base 110 to the body, including adhesives, projections,screws, pins, or other method. In accordance with one embodiment of theinvention, anchor 102 is advantageously a polyaxial bone screw, asdepicted, and anchor base 110 includes a bone screw chamber 112 forconformingly and movably receiving a polyaxial bone screw head 202.Anchor fastener 114 is provided, operative to secure bone screw head 202within anchor base 110, to thereby lock anchor 200 in a fixed positionwith respect to anchor base 110. In the embodiment of FIG. 1, anchorfastener 114 depicts a set screw, although other means may be providedto apply pressure or firmly secure an anchor, including collars,sleeves, and the like, as more fully disclosed, for example, in U.S.patent application Ser. Nos. 10/819,994 and 11/146,147, which areincorporated by reference herein.

FIG. 1 further depicts a receiver assembly 120 operative to securelyretain a stabilizing means 204, which may include a rod, depicted, or apin, brace, spring, cord, resilient extension, or any other stabilizingdevice, such as are disclosed, for example, in the patents andapplications previously incorporated, or as further described in U.S.patent application Ser. Nos. 10/443,755 and 10/762,533, which areincorporated by reference herein. Receiver assembly 120 advantageouslyincludes a stabilizer fastener 122, in this embodiment a set screw,operative to secure stabilizing means 204 in a fixed position withinreceiver assembly 120.

In the embodiment of FIG. 1, receiver assembly 120 and anchor base 110are mutually connected by a flanged connection 124, formed by a tenon,sash, projection, or tiebar 126, slideably retained within slide rails,flanges, or channels, including a receiver channel 128, and an anchorchannel 130. Tiebar 126 and or channels 128, 130 are advantageouslyformed with a lubricious material, favoring smooth movement of channels128, 130 in contact with tiebar 126. Example materials include ultrahigh molecular weight polyethylene (UHMWPE), PEEK, or otherbiocompatible polymer, or ceramic, polished metal, or other suitablebiocompatible material. In one embodiment, tiebar 126 is a polymer, andchannels 128, 130 are metal.

An access bore 132 extends from anchor fastener 114, through receiverassembly 120, whereby before stabilizing means 204 and stabilizerfastener 122 are installed, anchor 200 may be installed, or anchorfastener 114 may be installed, after which the aforementioned elementsmay be adjusted or tightened.

FIGS. 1A, 1B, and 1C illustrate alternative configurations for flangedconnection 124. In FIG. 1A, each of receiver assembly 120 and anchorbase 110 form a channel on three sides of tiebar 126A, in the manner ofa dovetail. It should be understood that the mating engagement of tiebar126 and channels 128, 130 may incorporate any of the more complex shapesknown in the art of forming dovetails, including fan shaped matingcomponents, which avoid a separation of the mated components.

In FIG. 1B, tiebar 126B is formed integrally, as a projection, withanchor base 110, and in FIG. 1C, tiebar 126C is formed integrally withreceiver assembly 120. In these embodiments, it may be advantageous toform a lubricious coating on one or more of the mating parts 126A/B andits corresponding channel. The embodiment of FIG. 1 or 1A enables thereplacement of tiebar 126 without a requirement to remove otherimplanted components of device 100.

Referring now to FIGS. 2 and 3, an embodiment of a stabilizing receiver100 is illustrated in perspective. FIG. 2 illustrates receiver assembly120 shifted, in this perspective, to the right with respect to anchorbase 110, and FIG. 3 illustrates receiver assembly 120 shifted to theleft. In this embodiment, tiebar 126 is held stationery within anchorbase 110 by a flange 134, indicated in FIG. 3. During its installation,tiebar 126 may be bent to pass over flange 134, whereupon after enteringthe channel, it may resiliently straighten and become trapped within thespace between channels 128, 130, and flange 134 on each end. Other meansof retaining tiebar 126 would be understood by those skilled in the art,including the use of pins, mating engagements, or a pressure fit.

Once tiebar 126 is inserted, receiver assembly 120 may slide laterallyin connection with anchor base 110, channel 128 and or 130 sliding alonga surface of tiebar 126. Receiver assembly 120 may not separate fromanchor body 110, however, as tiebar 126 now occupies a clearance betweenreceiver assembly 120 and anchor body 110 which enable their mutualassembly. Specifically, a projection of one of receiver assembly 120 oranchor base 110 was able to be inserted beneath a rail of the other,first on one side, then on another, until receiver assembly 120 wasseatable upon anchor base 110. A limiting projection 144 on one ofreceiver assembly 120 or anchor base 110 servers to limit lateralmovement of the respective parts. In FIG. 2, limiting projection 144 isintegrally formed as an edge or rail of anchor base 110. In FIG. 13A, itis visible as a boundary edge of channel 428. Limiting projection mayalso be installable onto either receiver assembly 120 or anchor base110, for example it may have the form of a pin or a screw which blocksthe relative movement of the respective parts at an intended limit oftravel.

In the embodiment illustrated in FIGS. 2 and 13, stabilizing fastener112 engages an aperture formed by two yoke extensions 140, through aninterlocking channel 142 in either stabilizing fastener 112 or yokeextensions 140, and a corresponding flange 144 in the other of the twoelements. In one embodiment, stabilizing fastener is turned about 90degrees to engage interlocking channel 142 and flange 144, after whichset screw 122 may be turned to secure a stabilizing means 204 which hasbeen placed between yoke extensions 140. Examples of this may be foundin U.S. patent application Ser. Nos. 10/819,994 and 11/146,147, whichare incorporated by reference herein. Other means may be provided toapply pressure or firmly secure stabilizing means, including for examplecollars, sleeves, screws and the like, as are more fully disclosed, forexample, in the incorporated patents and applications.

FIGS. 4 and 5 each depict a cross section of the receiver of FIGS. 2 and6, taken through a longitudinal centerline thereof, in which bone screwchamber 112 is visible. FIG. 5 illustrates the cross section of FIG. 4,rotated 90 degrees along a longitudinal axis. One or more wedges 136 areadvantageously driven into a space between an inner wall 138 of bonescrew chamber 112, and bone screw head 202, causing wedges 136 to bearagainst both elements, thereby improving a strength of connection ofbone screw 200 within receiver 100.

With reference to FIGS. 7-9, an alternative embodiment of the inventionin the form of an offset receiver 300, provided with an offset extension302 operative to displace offset receiving assembly 320 away from anaxial centerline of anchor base 310. Elements of anchor base 310 are asdescribed for anchor base 110, although as may be seen in FIGS. 7-9,access bore 132 is not obstructed after the installation of stabilizerfastener 122, or stabilizing means 204.

FIG. 8 illustrates offset receiver 300 in perspective, where it can beseen that offset extension 302 enables a location of offset receivingassembly 320 to a location removed from a location of anchor base 310.Moreover, offset extension 302 may advantageously have a complexgeometry, and in particular can extend in a first direction, then turn,and then extend in a second direction. In this manner, offset extension302 can reach around other objects, for example stabilizing elements, ora physiological structure, such as a bone pedicle. Further, offsetextension 302 can provide an offset in three dimensions, as may be seenin FIG. 12.

FIGS. 10 and 11 each depict a cross section of the receiver of FIG. 8,taken through a longitudinal centerline thereof. FIG. 11 illustrates thecross section of FIG. 10, rotated 90 degrees along a longitudinal axis,and with offset receiving assembly 320 not illustrated, for clarity.

In FIGS. 13-16, another embodiment of the invention is illustrated, inwhich defined therapeutically effective amounts of both lateral shiftingand axial rotation are enabled. In FIG. 13, pin 426 is illustrated,operative to replace tiebar 126, and to provide additional range ofmotion. In the embodiment shown, pin 426 is securely retained withinchannel 430, for example by being press fit, adhered, or threadablyengaged, and extends into channel 428 to be movable received therein;however, it should be understood that pin 426 could be securely retainedwithin channel 428, and movably extend into channel 430. Channel 428 hasthe shape of an elongated opening, bore, or channel, whereby receiverassembly 420 is retained in connection with anchor base 410, but is freeto rotate around its longitudinal axis to an extent defined by thelength of channel 428, and the relative dimensions of pin 426.Similarly, receiver assembly 420 is free to shift sideways with respectto anchor base 410, with an extent of shifting being dependent upon thelength of channel 428, and the relative dimensions of pin 426. Atherapeutically effective amount of shifting or rotation is more thanthat which would be allowed by mere incidental spacing or amanufacturing tolerance needed for smooth relative movement of matingparts, but not more than would be deleterious to the patient.

Advantageously, pin 426 is sufficiently long, and the dimensions ofchannel 428 sufficient constrained, to retain receiver assembly 420 inengagement with anchor base 410 throughout a full range of motion ofreceiver assembly 420 and anchor base 410, relative to each other.

While pin 426 is illustrated as being round, other shapes are possible,including elongated shapes. Additionally, pin 426 may fit loosely withinboth channel 428 and channel 430, being retained by some other means,for example a retainer engageable with pin 426, or a blocking memberplaced at an outlet of channel 428 or 430. While neither retaining meansare illustrated, their design is within the abilities of one skilled inthe art.

While pin 426 is illustrated in two parts, one on each side of receiverassembly 420, pin 426 could be formed as a single shaft or elongated pin426 passing from one side of receiver assembly to another (not shown).In this event, it may be advantageous to tighten anchor fastener 114prior to insertion of pin 426.

FIG. 13A illustrates the receiver of FIG. 13, rotated about alongitudinal axis 90 degrees, with only an outline of anchor base 410shown, in order to better view an embodiment of channel 428. FIG. 14 isa perspective view of an embodiment of the form of receiver depicted inFIG. 13.

FIG. 17 illustrates two receivers 100 mutually connected to astabilizing means 204, such as that shown and described, for example, inincorporated U.S. Patent application 2009/0299411 to Laskowitz.Stabilizing means 204, in this example, includes spool 258, end plate256, flexible intermediate portion 263, and cord 254, all having a formand function as described in the aforementioned application, with thefollowing distinctions. Receivers 100, in accordance with the instantinvention, are used to connect stabilizing means 200 to the patient. Assuch, certain movements of joint portions are not fully transmitted tomating joint portions, or to the stabilizing means connecting the jointportions. For example, shifting movements of joint portionsdirectionally aligned with the implanted direction of channels 128, 130,tend to cause relative movement of anchor base 110 and receiver assembly120, and thus less force is transmitted to adjoining joint portions.

More particularly, and with reference to FIGS. 18-19, flexion of asimplified series of joints is illustrated, in which three bones areprovided with receivers 100 in accordance with the invention. Thedrawings are diagrammatic, and are not to scale, to best illustrate afunctionality of the embodiments to be described. Each joint portion 206has been connected to a receiver 100 by anchor 200, whereby each anchorbody 110 moves and rotates with its respective joint portion. It shouldbe understood that while three levels, or jointed portions, areillustrated, any number of receivers and jointed portions may beconnected as shown and described herein. Similarly, it should further beunderstood that a single receiver may be used, wherein a portion ofstabilizing means 204 are connected to the body in some other way, forexample by a different form of connector, or by suture, staple, screw,glue, or any other method, and another portion of stabilizing means isconnected to receiver 100.

In FIGS. 18A-B, receiver assemblies 120 are of the type illustrated inFIG. 13, and are free to shift laterally and rotate axially, asdescribed herein. In FIGS. 18A-B, stabilizing means 204 is a rod that issubstantially inflexible relative to movement of the jointed bones 206.Each receiver assembly 120 is connected to rod 204, as describedelsewhere herein, although this connection is not illustrated, forclarity. As the joint segments are flexed in a direction indicated byarrow “C”, anchor bases 110 are each rotated, and brought closer to oneanother. As rod 204 does not bend, a rotating and a shifting force isimparted to an interface between anchor bases 110, and receiverassemblies 120. Consequently receiver assemblies 120 shift and rotaterelative to their respective anchor bases 110, as illustrated in FIG.18B. Viewed from a side, in FIG. 18A, it can be seen that ananterior/posterior flexion/extension is therapeutically inhibited, whilea lateral flexion is enabled.

With reference to FIGS. 19A-B, stabilizing means 204 is a flexible cord254 that readily bends, but is resistant to stretching, as more fullydescribed in the incorporated references. Other stabilizing componentswhich may be used together with cord 254, as described in theincorporated references, are not shown, for clarity. In thisillustration, the bones of the joints are engaged in both lateralflexion, indicated by arrow “C”, and flexion/extension, indicated byarrow “D”. Receivers 100 are representative of the embodiment shown inFIG. 2, which enable a lateral shifting of receiving assembly 120 andanchor base 110. As may be seen in the illustrations, cord 254 bends asit enters and exits receiver assemblies 120; however, a maximumseparation of the jointed bones is maintained. Further, it may also beseen that receiver assembly 120 is shifted from a centerline of receiver100, particularly in the lower two receivers 100 illustrated. Thisprovides additional range of motion for the patient, while maintainingan effective therapeutic stabilization.

Receivers 100 of the invention are useful in a wide variety of clinicalsituations, including total disc replacements, including situations inwhich both facets remain, or where one or more facets are removed. Inparticular, receiver 100 permits lateral or axial rotation, but preventsexcess shear forces being exerted upon the spine, which in turn couldcause instability and possibly alter the center of rotation of a spinalmotion segment. The invention may thus be used in conjunction with otherimplanted components, including an artificial or grafted discreplacement component. Examples of other implanted components which maybe used in conjunction with embodiments disclosed herein may be found inU.S. patent application Ser. Nos. 10/827,642; 10/909,210; 11/246,149;11/318,438; 11/364,160; 11/36,390; 12/623,725; 12/729,400; 12/466,680;12/632,267; and Ser. No. 12/699,648, which are incorporated by referenceherein.

FIG. 20 illustrates that a receiver 100 of the invention may be usedwith elongated bones of a body. Accordingly, receivers in accordancewith the invention may be used with bones or tissue anywhere in thebody, including the toe, foot, ankle, calf, knee, thigh, hip, spine,shoulder, head, jaw, upper arm, elbow, lower arm, wrist, hand, andfinger. Receivers 100 of the invention may additionally be used tostabilize rigid tissues, such as bones or cartilage, which have beendamaged, for example by disease or trauma. For example, the receiversmay be placed on opposite sides of a fracture, permitting therapeuticmovement in one plane, but not in another.

In accordance with the invention, prior to installation of receiver 100,it may be advantageous to first assemble wedges 136 onto anchor 200,pass anchor 200 through access bore 132 into bone screw chamber 112,seat receiving assembly 120 onto anchor base 110, and insert tiebar 126or pins 426, after which the assembly may be sterilized and packaged.Other parts are also sterilized and packaged. The assembly justdescribed may be installed into bone using the methods and toolsdescribed in the incorporated references, including the implantation andtightening of anchor 200 and stabilizing means 204. Prior to installingstabilizing means 204, anchor fastener 114 is installed and tightened.Advantageously, the same tool may be used to fasten anchor fastener 114and stabilizer fastener 122, for example a single hex head driver. Theforegoing assembly procedure may be altered, for example components maybe assembled prior to implantation, and disassembled at a time of use.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed herein above. In addition, unless mention was made above tothe contrary, it should be noted that all of the accompanying drawingsare not to scale. A variety of modifications and variations are possiblein light of the above teachings without departing from the scope andspirit of the invention.

All references cited herein are expressly incorporated by reference intheir entirety. In addition, unless mention was made above to thecontrary, it should be noted that all of the accompanying drawings arenot to scale. There are many different features to the present inventionand it is contemplated that these features may be used together orseparately. Thus, the invention should not be limited to any particularcombination of features or to a particular application of the invention.Further, it should be understood that variations and modificationswithin the spirit and scope of the invention might occur to thoseskilled in the art to which the invention pertains. Accordingly, allexpedient modifications readily attainable by one versed in the art fromthe disclosure set forth herein that are within the scope and spirit ofthe present invention are to be included as further embodiments of thepresent invention.

What is claimed is:
 1. A method of spinal stabilization comprisinginserting a first receiver assembly into a first bone member; insertinga second receiver assembly into a second bone member, wherein at leastone of the first receiver assembly and the second receiver assemblyincludes: a base, said base including a fastener connecting said base tobone; a receiver, said receiver positionable upon said base andincluding a first extension and a second extension for receiving anelongate rod therein; a flange associated with one of said base or saidreceiver; and a projection connected to the other of the base orreceiver associated with said flange, the projection being in appositionto said flange, wherein the receiver slides laterally while inconnection with the base, and wherein from a front view, the firstextension and the second extension form part of a U-shaped channel forreceiving the elongate rod therein and the projection is not outwardlyvisible inserting the elongate rod through the first receiver assemblyand the second receiver assembly.
 2. The of claim 1, wherein from thefront view, the projection is blocked by a surface of the base.
 3. Themethod of claim 1, wherein at least one of the first receiver assemblyand the second receiver assembly further include a second projectionconnectable to one of said base and said receiver.
 4. The method ofclaim 3, wherein the second projection is operable to limit a lateralmovement of said receiver relative to said base.
 5. The method of claim3, wherein the second projection is positioned adjacent to an end of theprojection.
 6. The method of claim 1, wherein said base includes achamber for receiving the fastener and a clamping element for clampingthe head of the bone screw within said chamber.
 7. The method of claim1, wherein said first extension and second extension are configured toreceive a set screw.
 8. The method of claim 1, wherein said flangeextends along at least two sides of the base or receiver to which it isassociated.
 9. The method of claim 1, wherein said projection is aflange extending along at least two sides of the base or receiver whichis not associated with said flange.
 10. The method of claim 1, wherein agap between said projection and said flange enables relative movementbetween said receiver and said base in the lateral direction.
 11. Themethod of claim 1, wherein the elongate rod is either rigid or flexible.12. The method of claim 1, wherein from a bottom to top direction, thereceiver has a bottommost width that is greater than or equal to anuppermost width.
 13. A method of spinal stabilization comprising:inserting a spinal system into a spine of patient, wherein the spinalsystem includes: a base having a first axis and a second axis, said baseincluding a bone screw chamber for receiving a bone screw therein; abone screw received within the bone screw chamber, wherein the bonescrew is polyaxial and includes a tapered shaft; a receiver connected tothe base having a first axis and a second axis, said receiver includinga first extension and a second extension, wherein the first extensionand the second extension form a channel therethrough; a flangeassociated with one of said base or said receiver; and a projectionconnected to the other of the base or receiver associated with saidflange, the projection being in apposition to said flange; and astabilizing member insertable between the first extension and the secondextension, wherein the stabilization member comprises a rod member,wherein the receiver slides laterally while in connection with the base,wherein at least one of the receiver and the base includes a limitingsurface to limit lateral movement of the receiver relative to the base,and wherein from a front view, the first extension and the secondextension form part of a U-shaped channel for receiving the stabilizingmember therein and the projection is not outwardly visible.
 14. Themethod of claim 13, wherein the spinal system further includes a setscrew received downwardly through the first extension and the secondextension.
 15. The method of claim 13, wherein the stabilizing member isrigid or flexible.
 16. The method of claim 13, wherein the projectioncomprises a tie bar, wherein the receiver slides relative to the basealong the tie bar.
 17. The method of claim 13, wherein from a bottom totop direction, the receiver has a bottommost width that is greater thanor equal to an uppermost width.
 18. The method of claim 13, wherein agap between said projection and said flange enables relative movementbetween said receiver and said base in the lateral direction.
 19. Themethod of claim 13, further comprising a limiting member for limitinglateral movement between the receiver and the base, wherein the limitingmember is positioned adjacent to an end of the projection.
 20. Themethod of claim 13, wherein the first extension and the second extensioneach have one or more indentations formed on a front surface or sidesurface thereof.